Boosting photoluminescence quantum yields of triarylboron/phenoxazine hybrids via incorporation of cyano groups and their applications as TADF emitters for high-performance solution-processed OLEDs

Cyano groups were introduced into the triarylboron/phenoxazine hybrids, and the resulting emitters not only exhibited distinct thermally activated delayed fluorescence (TADF) characteristics but also achieved a remarkable improvement in the photoluminescence quantum yields (PLQYs). The PLQYs of TB-1PXZ2CN and TB-2PXZ1CN are 0.67 and 0.75, which are 5.6 and 1.6 times higher than those of the respective non-cyano counterparts. Employing the two TADF emitters in solution-processed organic light-emitting diodes external quantum efficiencies (EQEs) of 9.7% and 11.4%, respectively, were achieved. Notably, the EQEs remained as high as 8.9% and 10.2% at a luminance of 2000 cd m(-2) with slight efficiency roll-offs of 8% and 11%, respectively.